The goal of this investigation is to study the behavioral development of social rejection and social isolation in children's peer groups. Because previous studies have been retrospective or correlative, conclusions about precipitant causes of social status are limited. In the present investigation, new peer groups will be constructed from randomly selected children who will not have had previous contact with each other. Those children will be brought together twice weekly over a period of four weeks, and will be given an opportunity to develop new social relations in a loosely-structured, free "play group." The behavioral interactions will be coded by "live" observers and will be recorded by a hidden video camera for later analysis. Behavior coding will take the form of a modified event record. At the end of the group experience, each child will be extensively interviewed about his friendships and social experiences. From these sociometric interviews, groups of rejected, isolated, and popular children will be identified, and their previous behaviors will be analyzed, in an effort to identify specific behavioral patterns which have anteceded each status. Behaviors of interest include social approaches, aggression, and responses to others' approaches. Sequential analyses and analyses of variance will be used to identify group differences and patterns. The investigation thus constitutes a short-term longitudinal study of the development of social status.